TRANSACTIONS OF SECTION D. 507 
phases with such in the fowl’s egg, artificially incubated, it is seen that in 
the latter they do not appear so early. This may in part be associated with 
the longer time that the fowl takes to completely incubate its eggs, but it is 
noteworthy that the discrepancy in the time of the appearance of the cor- 
responding stages of development in the case of the sparrow’s eggs may be 
further bridged over if one assumes that the naturally well-constructed heat- 
retaining nest allowed development to proceed during the laying of the clutch, 
that is to say prior to the period when the mother bird took on the task of 
incubating. 
4. British Pleistocene Canidae. By Professor §. H. Reynoups, M.A. 
Three species are found, the wolf, fox, and Arctic fox. There is no 
evidence of the existence in Britain, in Pleistocene times, of any animal 
that could be called a dog. The wolf, which is first found in Pliocene strata, 
abounded in England in Pleistocene times, its bones having been recovered 
from 47 out of the 51 deposits referred to. There are few records from the 
Scotch Pleistocene, probably owing to the lack of caves, but this explanation 
will not account for the scanty and generally fragmentary character of the 
wolf-bones found in Ireland, where they are known from only twb Pleistocene 
caves. The distribution of the fox in cavern deposits is almost identical 
with that of the wolf. The Arctic fox has been recovered at present from 
only four English Pleistocene deposits, and one Irish. The find described 
as Lycaon anglicus is thought by the author to be better regarded as a some- 
what abnormal wolf. 
While apart from any difference in size the skull of a fox is readily dis- 
tinguished from that of a wolf or dog by the depressions in the post-orbital 
processes of the frontals, it is extremely difficult, if not impossible, to 
find any valid distinctive character as between dogs and wolves. The most 
useful character, for which we are indebted to Studer, is the orbito-frontal 
angle. He regards skulls in which this angle measures 40°-45° as belong- 
ing to wolves, and as belonging to dogs skulls in which the angle is 
greater than 45°. The author’s measurements, while confirming Studer’s 
contention that the angle in question tends to be decidedly less in the wolf 
than in the dog, show that the distinction is not absolute, and cannot be 
relied on in all cases. 
5. The Réle of Visual Function in Animal and Human Evolution. 
By Grorae M. Gourp, M.D. 
The author sought to bring to better recognition the difficulties encountered 
in the creation and the adaptation of the eye to the environment, a large 
and intimate part of the environment being the animal and human body 
itself. The difficulties were grouped into those which relate to :— 
1. The embryology and optics of the eyeball. 
2. The réle of vision in the development of self-motility of the body. 
3. The progress from divergence to parallelism of the optic axes, or from 
laterality to forward-looking. 
4. The adaptations consequent upon the assumption of the vertical 
posture of the body. 
5. The development of the shading mechanisms of the retina. 
6. The struggle against astigmatism and other forms of ametropia, 
accommodational failure, cataract, ocular and systemic disease. 
Embryology is suggestive in the facts that the essential part of the eye, 
the retina, is cerebral substance pushed without the skull—‘ the brain comes 
out to see’; and, secondly, that at so early a period eye and muscular 
tissue are coincidently developed. Ubi motus ibi visus thus illustrates that 
